The Collaborative International Dictionary of English v.0.48:

Alkanet \Al"ka*net\ ([a^]l"k[.a]*n[e^]t), n. [Dim. of Sp.
   alcana, alhe[~n]a, in which al is the Ar. article. See
   Henna, and cf. Orchanet.]
   1. (Chem.) A dyeing matter extracted from the roots of
      Alkanna tinctoria, which gives a fine deep red color.
      [1913 Webster]

   2. (Bot.)
      (a) A boraginaceous herb (Alkanna tinctoria) yielding
          the dye; orchanet.
      (b) The similar plant Anchusa officinalis; bugloss;
          also, the American puccoon.
          [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Bugloss \Bu"gloss\, n.; pl. Buglosses. [F. buglosse, L.
   buglossa, buglossus, fr. Gr. ? oxtongue ? ox + ? tongue.]
   (Bot.)
   A plant of the genus Anchusa, and especially the Anchusa
   officinalis, sometimes called alkanet; oxtongue.
   [1913 Webster]

   Small wild bugloss, the Asperugo procumbens and the
      Lycopsis arvensis.

   Viper's bugloss, a species of Echium.
      [1913 Webster]

WordNet (r) 3.0 (2006):

alkanet
    n 1: perennial or biennial herb cultivated for its delicate
         usually blue flowers [syn: bugloss, alkanet, Anchusa
         officinalis]